24.1 Neurology for dentistry Flashcards
CN I.
- Olfactory
- Sensory
- Sense of smell
- Ask about change in smell
CN II.
- Optic
- Sensory
- Vision
- Visual acuity via Snellen chart, visual fields
CN III.
- Oculomotor
- Motor
- Extrinsic and extrinsic eye movements, levator palpebrae superioris
- Eye movements, accomodation reflex, pupil reflex, eyelid opening
CN IV.
- Trochlear
- Motor
- Innervates superior oblique muscle of the eye
- Eye movements
CN V.
- Trigeminal
- Both (motor and sensory)
- Sensation to the face, motor to muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani and tensor veli palatini
- Light touch, jaw movement, clenching of muscles
CN VI.
- Abducens
- Motor
- Lateral rectus muscle
- Eye movements
CN VII.
- Facial
- Both and autonomic (parasympathetic)
- M: Muscles of facial expression, posterior belly of digastric, stylohyoid and strapedius
- S: taste to anterior 2/3rds of the tongue
- Parasymp: lacrimal glands and salivary glands
- Test the facial muscles (branches TZBMC)
- Reduced salivation and loss of taste
CN VIII.
- Vestibulocochlear
- Sensory
- Hearing
- Weber and Rinne test
CN IX.
- Glossopharnygeal
- Both and autonomic
- M: stylopharyngeus muscle
- S: taste to posterior third of tongue and palate
- Autonomic: parotid gland
- Test gag reflex
CN X.
- Vagus nerve
- Both and autonomic
- M: pharyngeal constrictors, cricothyroid muscle, palatoglossus, palatopharyngeaus, muscles of larynx
- S: visceral sensation to heart and abdomen viscera, taste to epiglottis and root of tongue
- Motor parasympathetic: innervates the smooth muscle of the trachea, bronchi and gastro-intestinal tract and regulates heart rhythm
- Pt says ‘ah’ observe the uvula
CN XI.
- Accessory
- Motor
- Sternocleidomastoid and trapezius
- Askpt to shrug shooulders and turn head against resistance
CN XII.
- Hypoglossal
- Motor
- Muscles of tongue
- Stick tongue out
What is mydriasis?
Dilation of the pupil
What is ptosis?
Drooped eyelid
What cranial nerve is damaged?
- Cranial nerve III defect (oculomotor)
- Eyeball is down and out, pupil is dilated as constrictor muscle has lost its tone, ptosis, mydriasis
- Oculomotor nerve palsy
What cranial nerve is damaged?
- CN VI (abducens) nerve palsy
- Lateral rectus not functioning correctly
What cranial nerve is damaged?
- Hypoglossal (VII), left
- Muscles on left side are weaker and tongue curves towards the damaged side as it is a lower motor neuron defect
Compare a lower motor neuron defect vs upper motor neuron defect.
- Lower motor neuron defect = nerve itself affected
- Upper motor neuron defect = higher up brain/neuron issues
Example if hypoglossal nerve is damaged:
- Lower defect – tongue curves towards damaged side, in this case it is a left lower motor neuron defect
- Upper defect – tongue would curve away from damaged side
What cranial nerve is damaged?
- Right facial nerve palsy
- Lower motor neuron defect
- If it was an upper motor neuron defect you would still get some eyebrow furrowing/eyebrow sparing
What cranial nerve is damaged?
- Right accessory nerve palsy (XI)
- Most commonly seen in pts who have undergone neck dissection
- Accessory nerve is very narrow and easily damaged
What is a cerebrovascular accident?
A stroke
What are the 3 types of stroke?
- Ischaemic: caused by a thrombus or embolus in the brain, blocks the brain and causes an infarction
- Haemorrhagic (approx. 15%): caused by a bleed, causes infarction
- Transient ischaemic attack (TIA): not technically a stroke, temporary reduced blood supply to the brain but no infarction, known as a mini stroke, may go on to have a stroke
What are the risk factors for a stroke?
- Cardiovascular disease such as angina, MI, peripheral cardiovascular disease
- Previous stroke or TIA
- Atrial fibrillation, pts often on Rivaroxaban as prevention
- Carotid artery disease- atherosclerotic, plaque breaks off and spreads to carotid artery
- Hypertension
- Diabetes
- Smoking
- Vasculitis
- Thrombophilia
- Combined contraceptive pill
How is a stroke recognised?
FAST
- Facial weakness
- Arm weakness
- Slurred speech
- Time
What should you do if you suspect a stroke in dental practice?
- Call 999
- Do not give aspirin
- Give supplemental oxygen if saturation is below 92%, 15 litres per min
- Continue monitoring patient via ABCDE approach
- Get someone to take notes and note timings of onset of symptoms or any change of symptoms
- Handover to ambulance crew using SBAR format
- SBAR: situation, background, assessment, recommendation
How are strokes treated in hospital?
- CT to exclude haemorrhage
- Give 300mg if it is not a haemorrhagic stroke, continue 300mg aspirin daily for 2 weeks
- Thrombolysis: e.g. alteplase, a tissue plasminogen activator, breaks down clots and reverses effects of stroke, helps to save brain tissue
What is the secondary prevention of stroke following an ischaemic stroke or TIA?
- Clopidogrel 75mg daily (antiplatelet)
- Atorvastatin 80mg daily
What is motor neuron disease?
An umbrella term to describe a vairety of types of diseases affecting the motor neurons only (not sensory), a progressive and ultimately fatally condition.
Most common MND is ALS: amyotrophic lateral sclerosis
What is the presentation of MND?
- Insidious progressive weakness of all muscles
- Affects speech
- Usually first noticed in upper limbs
- Clumsiness, tripping over
- Slurred speech
- Dysphagia
- Lower motor neuron disease: muscle wasting, reduced tone and fasciculations in muscles
What is the management for NMD?
- No effective treatment
- Medication can ease symptoms
- Riluzole can slow progression of ALS and extend survival by a few months
- Pts usually die of respiratory failure or pneumonia
What is myasthenia gravis?
An autoimmue condition caused by antibodies attacking components of the post synaptic membrane.
More common in women under 40 and men over 60.
Linked with thymoma- tumour of the thymus gland.
What antibodies are present in pts with myasthenia gravis?
- 85% have acetyl choline receptor antibodies
- 15% have antibodies to muscle-specific kinase (MuSK) or low density lipoprotein receptor related protein 4 (LRP4) - both needed for creation of acetyl choline receptors
Receptors are blocked meaning AP can’t be generated.
What are the symptoms of myasthenia gravis?
The symptoms most affect the proximal muscles and small muscles of the head and neck. Leading to:
- Extraocular muscle weakness causing double vision (diplopia)
- Eyelid weakness causing drooping of the eyelids (ptosis)
- Weakness in facial movements
- Difficulty with swallowing
- Fatigue in the jaw when chewing
- Slurred speech
- Progressive weakness with repetitive movements
How is myasthenia gravis treated?
- Reverisble acetylcholinesterase inhibtitors e.g. pyridostigmine or neostigmine
- Immunosuppression e.g. prednisolone or azathioprine
- Thymectomy can improve symptoms even in patients without a thymoma
- Biologics
Describe biologics in relation to the treatment of myasthenia gravis.
- Monoclonal antibodies
- End in ‘mab’
- Rituximab targets B cells and reduces the production of antibodies
- Eculizumab targets complement protein C5, prevents complement activation and destruction of acetylcholine receptors
- Biologics have immunosuppresive actions
What are the dental implications of myasthenia gravis?
